1. Field of the Invention
This invention relates to assemblies having a support element and/or a chip and methods for shielding and protecting the same.
2. Description of Related Art
In the technical field of electronic packaging, a variety of different packages for integrated circuits have been developed in the past. For example, surface-mount devices have been developed that have a ceramic package (or module) with solder pads that provide connection to the integrated circuit. These solder pads may be made much smaller than the area required by a pin in previous pin-grid array (PGA) packages or dual in-line (DIP) packages, resulting in a higher connection density.
Surface mount modules may be mounted on a variety of different types of circuit boards, circuit modules or other system boards. A system board designed to receive a surface mount module typically provides landing pads that align with the landing pads on the module. Solder balls or solder bumps may be formed on either the module landing pads, the system board landing pads, or both. The surface mount module is then placed on the system board and the entire assembly is heated until the solder balls flow and form a good electrical connection between landing pads. The array of solder balls thus serve as an interconnect mechanism between the landing pads on the module and the landing pads on the system board.
As an example of surface mount modules, ball-grid array (BGA) and column-grid array (CGA) chip carrier modules have used arrays of solder balls or column (sometimes referred to as cylinders) as input and output connection. In this application, the term “solder balls” will be used generically to refer to the balls, bumps, columns, cylinders or other suitable connections used as surface mount module interconnects. With a dense array of solder balls covering one side of the module, BGA and CGA modules can provide a large number of input and output connections to the chip in the module without using excessive space.
In many applications the BGA or CGA technology is used in connection with the flip-chip concept. When the chips or modules are connected to the system board, the chips are flipped over and placed so that the array of solder balls are aligned with the corresponding array of landing pads on the system board. The chip and system board are then heated, allowing the solder paste to melt and flow for establishing the physical and electrical connection between the chip and the system board. In this application, the term “flip-chip” will be used generically to refer to a chip having contact elements, the chip being mounted onto a support element with contact elements facing the support element.